There is known a liquid treatment process in which a substrate such as a semiconductor wafer (hereinafter, simply referred to as “wafer”) is horizontally placed and the wafer is processed by supplying different kinds of processing liquids to the wafer in turn while rotating the wafer around a vertical axis.
The liquid treatment process is performed by a processing unit including a substrate holder configured to hold a substrate and a processing liquid supply mechanism configured to supply a processing liquid. Further, there is known a substrate processing system which is equipped with multiple processing units and a substrate transfer device configured to transfer wafers between the processing units and a carrier accommodating a multiple number of wafers therein.
In each of the aforementioned processing units, a multiple number of processing liquid supply mechanisms are provided to supply different kinds of processing liquids in turn. Furthermore, since the multiple processing units are provided in this substrate processing system, the substrate processing system is provided with a large number of processing liquid supply mechanisms.
Each processing liquid supply mechanism is equipped with a flow rate control mechanism such as a flow rate control valve configured to control a flow rate of the processing liquid. In order to adjust a supply amount of the processing liquid from each processing liquid supply mechanism, an appropriate opening degree of a valve body needs to be set based on characteristics of the processing liquid supply mechanism, such as a supply pressure or a viscosity of the processing liquid, a flow rate characteristic of the flow rate control valve, a pressure loss between an upstream side and a downstream side thereof, etc.
By way of example, in order to allow the flow rate of the processing liquid to approach a target supply amount by automatic control with high accuracy, a control parameter needs to be adjusted based on, e.g., a relationship between the opening degree (operation amount) of the valve body and the flow rate of the processing liquid. Accordingly, in the processing unit configured to supply the plural kinds of processing liquids, control parameter of the processing liquid supply mechanisms need to be adjusted for respective processing liquids having a great difference in physical property such as density or viscosity individually. Furthermore, since an optimum value of the control parameter may be changed according to the range of a supply flow rate of the processing liquid, the control parameter may also be adjusted when a processing recipe for the wafer is changed. In addition, since the optimum value of the control parameter also relies on a characteristic of the processing liquid supply mechanism, the control parameter needs to be adjusted differently for the individual processing units even when the same kind of processing liquid and the same processing recipe are used. Thus, in the overall substrate processing system including the plural processing units, the number of processes required for adjusting the control parameter is too many.
Described in Patent Document 1 is a technique of recording a flow rate of a processing liquid that flows through a processing liquid supply line in a substrate processing apparatus configured to vary a supply flow rate of the processing liquid based on an opening degree of a needle value. According to this document, if a processing condition or the supply flow rate of the processing liquid is set, the opening degree of the needle value is adjusted in advance based on this setting result, so that the appropriate flow rate of the processing liquid is set from the beginning of the supply of the processing liquid.
In the technique disclosed in Patent Document 1, however, a relationship between a position of the needle valve and the supply flow rate needs to be investigated in advance for every single set flow rate. Accordingly, whenever a processing recipe or the like is changed, an operation for investigating this relationship is additionally required.
Patent Document 1: Japanese Patent Laid-open Publication No. 2010-123709 (Claims 2 to 4, and paragraphs [0015] to [0021])